The subject matter herein relates generally to a communication cable that includes a plurality of insulated conductors and a helically-wrapped shielding tape that surrounds the insulated conductors.
Communication cables include insulated conductors that extend alongside each other for a length of the communication cable. For instance, a communication cable may include a pair of the insulated conductors extending parallel to each other. Examples of such communication cables include twin-axial cables, which are also referred to as Twinax or twin-axial cables. The insulated conductors may be surrounded by a shielding tape that, in turn, is surrounded by a cable jacket. The shielding tape includes a conductive foil that functions to shield the insulated conductors from electromagnetic interference (EMI) and generally improve performance.
In a conventional twin-axial cable, the shielding tape is a composite tape that includes a plastic backing and a conductive foil. The plastic backing increases the strength of the shielding tape and protects the conductive foil from tearing or other damage. Like other types of tape, the shielding tape includes a lateral edge at an end of the shielding tape and a pair of longitudinal edges that extend parallel to each other along a length of the shielding tape. When the shielding tape of the conventional twin-axial cable is wrapped around the insulated conductors, the conductive foil typically faces radially-inward and engages the insulated conductors. The shielding tape is helically wrapped around the insulated conductors such that the longitudinal edges repeatedly wrap around the insulated conductors in a helical manner.
In the conventional twin-axial cable described above, the shielding tape has numerous “wraps” around the insulated conductors in which each wrap is moved further along the length of the cable with respect to the prior wrap. Each subsequent wrap extends partially over the prior wrap such that a portion of the conductive foil from the subsequent wrap overlaps with a portion of the plastic backing from the prior wrap. Consequently, the conductive foil from the subsequent wrap is electrically isolated from the conductive foil of the prior wrap along this overlapped region. More specifically, the conductive foil of the subsequent wrap and the conductive foil of the prior wrap are separated from each other by the plastic backing of the prior wrap. It is suspected that this electrical isolation along the overlapped region, which also extends around the insulated conductors in a helical manner, causes a “suck-out” effect that limits the data transmission speed of the cable. For example, conventional twin-axial cables having a wrapped shielding tape may have a maximum data transmission speed of 14 Gigabits/second (Gbps).
An alternative twin-axial cable has been used in which the shielding tape is not repeatedly wrapped around the insulated conductors. Instead, the shielding tape is folded over the insulated conductors such that one longitudinal edge of the shielding tape overlaps the opposite longitudinal edge. In this configuration, the longitudinal edges extend generally parallel to the insulated conductors (or a centerline of the cable). Although the folded configuration reduces the suck-out effect, this alternative cable has a limited flexibility compared to the communication cables having shielding tapes that are helically wrapped.
Accordingly, there is a need for a communication cable having a helically-wrapped shielding tape that reduces the suck-out effect.